...I don't give a rats @$$ about this constant, goes-nowhere debate...however...

Inside your loudspeaker there are short, isolated lengths of wire that go from the appropriate points of the Xover circuit board to the appropriate drivers...if so equipped, there is a jumper that joins the LF and HF sections of said Xover...

Now, if you bi-wire, you are essentially taking those short, relatively protected wires and extending them outside of their little cabinet-style home and exposing them to all manner of EFI/RFI/EIEIO...not to mention adding a bit of resistance and capacitance which changes the make-up of the specifically designed crossover...

jimHJJ(...you do the math...)